It was Mad Monday.

Nationwide, an estimated 850 million items are mailed on what is annually the busiest day of the holiday season for the U.S. Postal Service — the Monday of the last full week before Christmas.

Hawai'i contributions have hovered at roughly a million in the last few years, give or take a few thousand Mele Kalikimaka cards and packaged fruit cakes.

"Traditionally, this is the Mad Monday," said Bo Mahoe, supervisor of customer service at the Ala Moana post office. "Everybody went shopping over the weekend, so they will flock to the post office. Historically, traditionally and mathematically, it has been the busiest day."

If it’s any consolation, today started slow for the Ala Moana post office. There were only 50 people waiting in line when it opened at 8:30 a.m. Yesterday, the opening line was 250 people long, Mahoe said.

"They either didn’t want to run the marathon or go to church," Mahoe said.

He estimates about 7,000 cards, letters and packages passed through the busy office.

Across town at the Honolulu post office, Obed Okashige, the station manager, today said the holiday rush was just beginning to take shape.

There were only 25 to 30 people waiting when he opened this morning. The crush of last-minute mailers should rise through Thursday and last until next Monday, maybe even Tuesday.

His staff is more than ready, he said.

"They kind of look forward to this time of year," Okashige said. "It seems as though when they do this, they feel like they are helping their customers get that Christmas spirit across."

As for your apprehensive letter carriers, well, they know what’s coming.